二阶样条小波卷积法分辨重叠化学信号

首次提出了二阶样条小波卷积分峰法, 通过二阶样条小波与重叠化学信号的卷积运算, 确定出各组分的峰位置和峰宽之比, 再利用样条函数构造峰分辨器, 分辨重叠信号, 同时给出了方法的理论依据, 并对参数的选择进行了讨论. 对大量仿真信号和实验信号的处理实践表明, 分辨后信号可以达到基线分离, 峰位置相对误差小于0.2%, 峰面积相对误差小于4.0%, 即使对于重叠严重的信号, 也能获得满意结果. 该方法可以直接用于含噪音的及多个峰的重叠体系, 是一种分辨重叠信号的有效新方法.     

连续样条小波变换用于分解重叠峰的研究

以B-样条小波为分析小波，提出了用于分析化学重叠信号解析的新方法——连续样条小波变换，结果表明：连续样条小波变换应用于分析化学信号的处理，能使峰变窄同时还能提高信号的信噪比，是一种新型有效的重叠信号解析方法，能从含噪声重叠信号中直接得到重叠峰的峰数目及其相应的峰位置。     

用于电分析化学重叠信号分辨的样条小波自卷积法

以正弦函数为分辨因子与样条小波滤波器相作用,使其构成样条小波自卷积法的峰分辨器,利用样条小波峰分辨器可以直接分开计算机模拟的不同类型的重叠双峰,分峰前后峰面积和峰位置的相对误差均小于5．0％;将其应用于电分析化学重叠信号的实验数据处理,得到较满意的结果。同时,为样条小波峰分辨器分辨因子提供了新的选择。     

二次微分与样条小波自卷积联用分辨重叠伏安峰

本文采用二次微分法寻找重叠峰的各个峰位置，再利用样条小波自卷积（SWSC）方法直接对重叠的伏安峰进行处理，取得了较好的结果。被处理的重叠峰可达到基线分离，且峰位置的相对误差小于3．0％（完全掩盖峰为5．39％），峰面积的相对误差小于2．0％。方法不用于铅（Ⅱ）－铊（Ⅰ）体系的微分脉冲伏安信号处理，取得满意的结果。     

重叠伏安峰的样条卷积法分辨

建立了分辨重叠峰的样条卷积法；利用三阶样条函数构成的峰分辨函数与原信号进行卷积，直接对重叠的伏安峰进行处理，取得了较好的结果；被处理的重叠峰可达到其线分离，且峰位置的相对误差小于3．0％（完全重叠峰为5．4％），峰面积的相对误差小于2．0％；应用于镉（Ⅱ）－铟（Ⅲ）实验体系的微分脉冲伏安信号处理，取得满意的结果。     

样条小波变换用于分辨重叠伏安峰的研究

将样条小波变换技术用于分辨重叠的伏安峰 ,以选定的分辨因子作用于样条小波滤波器 ,使之成为峰分辨器 ,用它来直接处理重叠的伏安峰 ,取得了较好的结果 .被处理峰可达到基线分离 ,且峰位置的相对误差小于 3.0 %,峰面积的相对误差小于 5 .0 %,方法简便易行 .讨论了各种影响分峰效果的因素 ,包括不同的分辨因子及样条小波基等 ,并应用于镉 (Ⅱ ) 铟 (Ⅲ )和铅 (Ⅱ ) 铊 (Ⅰ )体系的实验数据的处理以验证该方法     

样条小波和Fourier变换联用技术在分析化学中的应用

探讨了样条小波和Fourier变换方法的算法及应用特征,将两种方法联合使用,设计出了一种新型的数字滤波器,使两种方法互相取长补短,使各自的优势能得到充分发挥.优选了处理低信噪比分析化学信号的滤波参数.不仅能使结果峰形高度保真,克服样条小波分析方法的不足,而且可对高噪声信号进行处理.     

小波变换在重叠化学信号解析中的应用

将小波变换应用于重叠化学信号的分辨与处理,由于在噪声较大的情况下二阶导数法很难从噪声中区分出微弱信号峰,故通过小波卷积法确定各个组成峰的位置.在信噪比相对较低的情况下明显优于二阶导数法,然后利用小波滤波器处理数据,处理后的峰可达到基线分离,峰位置和面积基本不变.将此方法应用于单一成分的正丁酮、正丁醛以及乙醇、正丙醇、异丙醇、正丁醇、正戊醇和仲辛醇6种醇类物质的混合物处理,得到了满意结果.     

基于提升格式的小波变换用于处理化学信号

将提升haar小波变换应用于对不同类型含高噪声化学信号的处理,提出1种用于高噪声化学信号中滤除噪声的快速新方法——提升小波滤噪法,并使之与重叠峰分辨技术联用;以优选的小波分解层数对低信噪比的分析化学信号进行基于提升格式的小波变换处理,取得满意的结果;方法简单、快捷、准确、易行．运算速度是传统小波变换的一半,对高噪声化学信号的处理结果信噪比提高几百倍,峰位置相对误差小于1．5％;应用于氨基酸体系毛细管电泳检测信号的处理,有效降低了实验噪声的影响,分辨提取了难以察觉的信号．结果峰形变窄,峰高增加．大大提高了峰的分辨率．验证和显示了方法的可行性和优越性。     

小波分形分析重叠峰信号

用连续小波变换与分形理论相结合的小波分形峰位法对含噪重叠信号峰位置的提取进行了研究, 同时考察了信噪比和分离度对该法提取峰位置的影响; 结果表明 该法是一种提取含噪重叠信号中各单独峰峰位置的有效工具, 即使对于重叠程度和噪声干扰严重的信号也能得到较好的结果; 将其用于 Cd(Ⅱ )和 In(Ⅲ )重叠伏安信号的处理, 峰位置提取的相对误差小于± 1%; 该法具有准确、快捷、简便易行等特点, 发展前景广阔.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.